In response to demands in the market, there have been proposed many technologies which allow a vehicle to urgently travel several hundreds kilometers when a pneumatic tire thereof is punctured during traveling. These many proposals include a technology that allows for run-flat operation by supporting a punctured pneumatic tire with a support member mounted on a rim in the cavity of the tire seated on the rim.
The above run-flat support member comprises an annular shell having a support surface located radially outward with two convexly curved surface sections arranged widthwisely thereof and a leg structure in an open state disposed radially inward, and elastic rings attached to two leg portions of the leg structure, and is supported on the rim via the elastic rings. The run-flat support member allows existing wheels to be used without any specific modifications, and can therefore be advantageously adopted without causing confusions in the market (see Japanese Patent Application Publication Nos. 10-297226 and 2001-519279, for example).
Wheels in common use comprise a disc and a rim fixed to the outer peripheral edge of the disc in such a manner that the widthwise center of the rim is off set towards one side (vehicle inner side), thereby increasing the space of the vehicle inner side surrounded by the disc and rim to accommodate parts mounted on the vehicle.
A tire/wheel assembly including the above run-flat support member mounted on a wheel with such an offset rim has such a problem that a portion of the tire supported by one convexly curved surface section located on the opposite side (vehicle outer side) of the rim to the offset side is more subject to destruction than a portion of the tire supported by the other convexly curved surface section located on the offset side (vehicle inner side) during run-flat operation, which is one of the causes that degrade durability in run-flat mode.